1. Field of the Invention
This invention relates to an image processing apparatus and an incorporated image reducing circuit therefor for an image information filing system and the like in which image information read by an image read-out device, for example, an image scanner is compressed and encoded to be stored in a storage medium such as an optical disk, or compressed and encoded image information is expanded to be restored to original image information for displaying or hard copying when necessary.
2. Description of Related Art
Recently, for the purpose of rationalization for increasing business data processing, so-called image information filing systems are being developed and being brought to practical use. The image information filing system is generally an unit, for example, a Sanyo Electric Co., Ltd.'s model SOF-M88 which storing documents, drawings and the like in a large capacity storage medium in page unit image information (filing) and read stored image information to display it on a display device or produce hard copies of it when necessary.
In such an image information filing system, image information to be filed is obtained from optically reading documents, drawings and the like of original images by an image information read-out device such as an image scanner to convert them into dot data. Then image information is processed for editing and compressed and encoded to be stored on an optical disk.
Now, an image size used in the field of so-called electronic filing systems is the A3 size and a resolution of the image scanner is about 400 dpi (Dots Per Inch) as standard. But the resolution of a CRT display of the display device is far less than 400 dpi. Therefore, when displaying the original image on the CRT display or producing a hard copy, it is necessary to reduce a number of dots, that is, to perform reducing processing. Such a reducing processing of an image is implemented so far by a dedicated LSI, for example, a MATSUSHITA ELECTRONICS Co., Ltd.'s model MN8617 or the like.
In the case of displaying on the display device such as a CRT display image information read by the image scanner, image information is generally stored once in an image memory and thereafter reduced by the dedicated LSI and displayed.
For example, when reducing A3 size image information with a resolution of 400 dpi (4864.times.6560 dots) into A4 size image information with a resolution of 200 dpi (1728.times.2304 dots), assuming that a time required for the image scanner to read a main scanning one line is 1 ms, a reducing processing speed by the MN8617 is 0.3 .mu.s/bit, then EQU time required to read: EQU 1 ms.times.6560 lines=6.56 s EQU time required for reducing processing: EQU (4864.times.6560+1728.times.2304).times.0.3.times.10.sup.-6 =10.8 s
and a total time for start-up of reading the original image to start-up of displaying image information is approximately 18 s.
In order to display a reduced image, encoded, and stored in a storage medium such as an optical disk, it is required to expand and decode this compressed, encoded and optical disk-stored image information to restore the original image information and thereafter reduce it to display the image. In this case, the decoding process requires several seconds, in addition the reducing process requires about 10.8 seconds as mentioned above. Such a time is only a boring waiting time for the image information filing system operator and reduces business data processing efficiency.
In view of this situation, Japanese Patent Applications Laid-Open No. 64-32383 (1989), No. 64-32384 (1989) and No. 1-276275 (1989) have been proposed.
The invention of the first Japanese Patent Application Laid-Open No. 64-32383 (1989) is substantially the same as the No. 64-32384 (1989) and comprises:
"first storage means for storing stored information; PA1 first processing means for searching for desired stored information from stored information stored in the first storage means; PA1 second storage means for temporarily storing stored information searched for by said first processing means; PA1 display means for displaying stored information searched for by the first processing means; PA1 recording means for recording and outputting stored information searched for by the first processing means; and PA1 second processing means for simultaneously controlling a processing of storing stored information searched for by the first processing means into said second storage means and a processing of making the display means display stored information and a processing of making the recording means record and output the stored information."
Further, first processing means includes decoding means for decoding stored information searched for by storage means, and second processing means includes enlarging/reducing means for enlarging/reducing stored information searched for by first processing means.
More concretely, the above invention performs in parallel a processing of restoring encoded information already compressed, encoded, and stored in an optical disk unit which is the first storage means to image information by decoding means and storing restored image information into the second storage means which is a page memory and a processing of displaying restored image information on display means in a displayable reduced form, and a processing of printing out restored image information by a recording means which is a printer.
However, in the above invention, enlarging/reducing means is not directly connected to a bus and provided in second processing means, thus its usage is limited. For example, in the case of recording the original image, processings of enlarging/reducing means used for displaying the original image on the display device are not performed in parallel, thus a waiting time arises as usual.
Further, in the above invention, when some components are operated in parallel, it is required to initialize each component from the viewpoint of software, as a result a time for signal processing is required.
The invention of the third Japanese Patent Application Laid-Open No. 1-276275 (1989) discloses image information processings in which when decoding compressed, encoded, and stored image information, and when reading the original image to compress and encode it, simultaneous enlarging/reducing process reduces a number of access times against image memory to increase a process speed. But in the system of this invention, image information is processed only through a path along code decoding means, enlarging/reducing means and an image display (print out), or a path along a read-out device for the original image, expanding/compressing means and code decoding means. Therefore, parallel processings can not be implemented in such a way that a read original image is processed through enlarging/reducing means to be displayed and simultaneously is compressed and encoded to be stored in an optical disk.